1. Technical Field
The invention generally relates to transducers and, more particularly, to transducer dynamic compensation based on ambient conditions.
2. Related Art
Almost all vehicles and other audio systems include loudspeakers to provide sound based entertainment to listeners. In general, loudspeakers are transducers utilizing electrical signals to reproduce sound. In the prior art, heating resulting from the electrical signals supplied to a loudspeaker voice coil may be determined and the loudspeaker sound performance may be compensated based on the heating.
The performance of loudspeakers is also affected by ambient conditions such as temperature, humidity and barometric pressure. As the ambient conditions vary, the loudspeaker undergoes changes. These changes are most diverse at ambient condition extremes that audio systems and vehicles experience throughout many parts of the world. For example in parts of Canada and Sweden vehicles will be operated at temperatures between −40° C. and +40° C. throughout annual season changes. With sun shining on vehicles, interior cabin and trunks may reach temperatures over +80° C.
The effects of variations in ambient conditions may cause changes up to 100% or greater in some loudspeaker parameters, for example resonance frequency. These changes have implications in at least two areas, namely, quality of sound and robustness. Thus, the loudspeaker will perform differently at different ambient conditions. These variations in performance may cause a change in the quality of the reproduced sound. For example, there may be a difference in the frequency response as the ambient temperature varies.
Robustness refers to the durability of the loudspeaker. When a loudspeaker is operating at extreme ambient conditions the loudspeaker may experiences different mechanical and thermal stresses that can impact the robustness and thus life of the device. The cause of ambient condition induced changes in loudspeaker performance may be due to changes in the properties of the suspension components. Ambient condition induced performance changes may also affect the loudspeaker magnet energy level. As the magnet energy level changes with changing ambient conditions, the force applied to the moving components may be affected. Accordingly, a need exists for loudspeaker dynamic ambient condition compensation.